Sunday, May 13, 2007

Lauren's New and Hot (Week 7)

This New York Times article From DNA Analysis, Clues to a Single Australian Migration discusses how it was previously thought that Australia and Papua-New Guinea were populated by several migrations, but that now based on mitochondrial DNA and Y chromosomes of aborigines, scientists can trace the ancestry of all aborigines back to one group that migrated 50,000 years ago. Until very recently, this population has been genetically isolated from all other human populations.

It was previously thought that dingos had to have been brought by later migrations, so this new information means that either dingos were acquired through trade with other groups of people, or that there were subsequent migrations of people with dingos, and that the later immigrants died out without a trace. Also, a change from thin bones 45,000 years ago to thicker bones around 20,000 years ago led researchers to suspect that some aborigines bred with Homo Erectus, but the evidence of only one migration indicates that the changes in bones were due to adaptation of the existing aborigine population.

Based on the DNA, researchers have traced the migration of the ancestors of the aborigines from India (a major stopping point out of Africa) to Australia. This migration probably took about 5,200 years to complete. While aborigines never bred much with other groups of people since leaving Africa, their present morphology is still significantly different from of their African ancestors. Based on fossil evidence in Australia, these morphological changes are due to genetic changes after the migration.

Lonesome George (again). Another New York Times article by the author of the article Becca posted last week, At Last, Hope for Lonesome George lists names suggested by various readers for the name of George’s potential mate. The final decision appears to be that Esperanza (Spanish for Hope) would be the best name for her- if she exists, for as long as she lives there will be hope for Pinta tortoises. This article does not really have any news in it, but I thought it would be fun to mention given that we have discussed Lonesome George the past two weeks.

While not new and hot, this does relate to Josh’s New and Hot last week, and our discussion of the distinction between chimpanzees and humans. This page includes several articles discussing the blurred line between human and chimp ancestors, and suggests that humans and chimps did interbreed shortly after the two species diverged, and that we have evolved to be more different since then.

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